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.TH CACHEFLUSH 2 2015-02-21 "Linux" "Linux Programmer's Manual"
.SH NAME
cacheflush \- flush contents of instruction and/or data cache
.SH SYNOPSIS
.nf
.B #include <asm/cachectl.h>
.sp
.BI "int cacheflush(char *" addr ", int "nbytes ", int "cache );
.fi
.SH DESCRIPTION
.BR cacheflush ()
flushes the contents of the indicated cache(s) for the
user addresses in the range
.I addr
to
.IR (addr+nbytes-1) .
.I cache
may be one of:
.TP
.B ICACHE
Flush the instruction cache.
.TP
.B DCACHE
Write back to memory and invalidate the affected valid cache lines.
.TP
.B BCACHE
Same as
.BR (ICACHE|DCACHE) .
.SH RETURN VALUE
.BR cacheflush ()
returns 0 on success or \-1 on error.
If errors are detected,
.I errno
will indicate the error.
.SH ERRORS
.TP
.B EFAULT
Some or all of the address range
.I addr
to
.I (addr+nbytes-1)
is not accessible.
.TP
.B EINVAL
.I cache
is not one of
.BR ICACHE ,
.BR DCACHE ,
or
.BR BCACHE
(but see BUGS).
.SH CONFORMING TO
Historically, this system call was available on all MIPS UNIX variants
including RISC/os, IRIX, Ultrix, NetBSD, OpenBSD, and FreeBSD
(and also on some non-UNIX MIPS operating systems), so that
the existence of this call in MIPS operating systems is a de-facto
standard.
.SS Caveat
.BR cacheflush ()
should not be used in programs intended to be portable.
On Linux, this call first appeared on the MIPS architecture,
but nowadays, Linux provides a
.BR cacheflush ()
system call on some other architectures, but with different arguments.
.SH BUGS
Linux kernels older than version 2.6.11 ignore the
.I addr
and
.I nbytes
arguments, making this function fairly expensive.
Therefore, the whole cache is always flushed.

This function always behaves as if
.BR BCACHE
has been passed for the
.I cache
argument and does not do any error checking on the
.I cache
argument.
